LOS ANGELES - Five people were wounded, including a student who was shot in the head, when a gun went off in a Los Angeles middle school on Thursday, and a 12-year-old girl was taken into custody, police said.

The girl, whose name was not released, was booked at a juvenile detention facility on a charge of negligent discharge of a firearm, said officer Tony Im of the Los Angeles Police Department.

Im declined to say if investigators believed the girl deliberately opened fire at Salvador B. Castro Middle School near the city's downtown district. Mayor Eric Garcetti told local KABC-TV at the scene that it was unclear if the shooting was accidental.

"We're unclear whether a gun went off or if it was an intentional shooting," Garcetti said. "Luckily there are no fatalities or serious injuries."

Jordan Valenzuela, 12, told The Associated Press he was in the classroom next door when he heard a loud bang. He said he talked to the girl just after the shooting and she was sobbing.

"She was like, 'I didn't mean to. I had the gun in my backpack and I didn't know it was loaded and my backpack fell and the gun went off,'" he said.

The shooting was reported just before 9 am, two students were hit directly by gunfire and three other victims were hit by shrapnel, police said.

A 15-year-old boy was hit by gunfire in the left temple and was rushed to hospital.

He had no damage to "vital structures," doctors said, adding they were cautiously optimistic he would survive.

A 15-year-old girl was hit in the wrist and was in stable condition, Los Angeles Police Department spokeswoman Wendy Reyes said.

The three people with slight injuries from shrapnel ranged in age from 11 to 30 years old, official said.

Authorities said they were trying to determine how the gun was brought on campus. The incident triggered a lockdown of the campus and a neighboring high school. Parents swarmed the area seeking to be reunited with their children.

"As a parent, this is everyone's worst-case nightmare," Los Angeles Police Department deputy chief Robert Arcos said at a news conference.

Reuters - Ap